Nano particles, especially metal nano particles have very special properties which are directly related to their dimensions and to the fact that a large ratio of the atoms in the particle are in the surface of the particle or at particle and grain boundaries. These properties include optical properties, sintering and diffusion properties, electrical properties like capacitance, impedance and resistance, catalytic activity and many others.
These improved properties have a range of uses and applications; e.g. catalysts for chemical reactions, electrodes, fuel cells, medical devices, water cleaning technologies, electronic devices, coatings, and more.
U.S. Pat. No. 5,476,535 to the applicant present a method for the production of nano-powders, especially of silver. This process comprising the steps of (a) forming an aluminum-silver alloy of a specific blend composition; (b) leaching the aluminum ingredient by a series of consequent leaching steps wherein a fresh leaching agent is reacting the treated solid material, providing a gradually porous and homogeneous silver alloy. Ultrasonic oscillations are applied in step (c), disintegrating the agglomerate and enhancing the penetration of the leaching agent into the ever growing porous of the alloy by the application of a plurality of ultrasonic oscillations. The leaching agent is leaving silver agglomerate in step (d), and then the agglomerate is washed and dried in a final step.
According to U.S. Pat. No. 6,012,658 to the applicant et al., the very same process was used as is to form metal flakes. Thus, the following two main steps were introduced: comminuting the alloys obtained by the aforementioned U.S. Pat. No. 5,476,535 into defined particles, and then faltering the obtained particles into strip-like highly porous alloys of predetermined characteristics.